1. Field of the Invention
The present invention relates to a scheduling method available in a router, and more particularly, to a router for efficiently scheduling a packet with a long packet length, such as a jumbogram or a jumbo packet, and a method therefor.
2. Description of the Related Art
Due to development of a high-speed networking technique, a network must transmit a large amount of data exceeding a processing capacity of a computer. To process such a large amount of data at a high speed, a CPU of a computer inevitably consumes many resources, which causes performance deterioration of the computer. To solve such a problem, it is necessary to reduce the number of CPU clock cycles consumed by data processing. An approach for this is to increase the length of a packet.
The length of a Maximum Transmission Unit (MTU) is recommended differently according to a protocol. The MTU represents a maximum size of a packet or frame capable of being transmitted through a packet/frame-based network such as a TCP/IP network. A packet with a maximum length of 64K bytes is used in IPv4 (Internet Protocol version 4). A jumbo frame with a length from 1518 to 9K bytes (maximum) is used in a giga-bit Ethernet. Also, a jumbogram with a length from 64K to 4 giga bytes (maximum) is used in IPv6. Hereinafter, a jumbo frame or a jumbogram with a length exceeding 1500 bytes are referred to as a “jumbo packet”, and a packet equal to or smaller than 1500 is referred to as a “general packet”.
A representative field in which such jumbo packets are used is a Storage Area Network (SAN) area. Studies into transmission of jumbo packets through a network are currently underway by ETF/DTF, Internet2, DoE, NASA, etc. However, the jumbo packet has shortcomings in compatibility with existing systems, which prevents standardization and spread of the jumbo packet.
FIG. 1 shows a configuration of a conventional router for scheduling a jumbo packet.
Referring to FIG. 1, a conventional router includes a stream classifier 100, a buffer unit 100 and a scheduler 120.
The stream classifier 100 classifies input packets according to their destination addresses and transfers the classified packets to the buffer unit 110. The buffer unit 110 stores the classified packets separately according to their corresponding destination addresses. Since the conventional router does not classify packets into general packets and jumbo packets, general packets and jumbo packets are mixed and stored in the buffer unit 110. The scheduler 120 decides an output order of packets stored in queues 112 of the buffer unit 110, according to a round-robin method or other scheduling methods, and outputs the packets in the decided output order.
Since the conventional router shown in FIG. 1 performs scheduling without classifying general packets and jumbo packets, packet transmission delay and packet loss may occur. Furthermore, in the case where delay-sensitive packets such as VoIP (Voice of IP) are processed at the same time with jumbo packets, serious packet loss as well as deterioration of service quality of VoIP can occur.